The Beginning
by Silverado17
Summary: This is my first sastiel story. It's a prequel to the story I'm currently working on. Basically, it's about how Sam and Cas discover they're both secretly pining over each other.
1. Chapter 1

_**AN: So, as I believe I may have already mentioned, I am working on a new story right now. This is the prequel to that story. It is of the sastiel/sassy variety. Don't like, don't read. There will be one chapter and an epilogue. This story can be read without the rest of the story, which will be posted separately from this. There are warnings that apply with the actual story, but they don't apply to this so I'm not going to waste my time or yours by posting them here. At the beginning of this chapter, we see a drunk Sam. I have never been drunk before (sue me), so this may or may not be an accurate representation. Please don't judge me for that portion of the story. I don't think there are any real spoilers as long as you know who Sam, Dean, and Cas are; and this isn't set in any particular point in time in the show. Just know both Sam and Dean are human and both have their souls, and Cas is 100% an angel.**_

 _ **Disclaimer: If I owned Supernatural, you would be watching this instead of reading it.**_

* * *

 **The Beginning  
(A Prequel)**

Sam, Dean, and Castiel all decided to go to a bar to celebrate their latest successful hunt – a ghost – that had been completed without injuries to any of them. The three of them got a table, but it wasn't long before Dean was playing – hustling, really – a game of pool. Sam and Cas kept drinking, and Sam ended up drunk. As an angel, it was possible for Cas to get drunk, but it took a lot of alcohol, so it wasn't likely to happen tonight.

Sam soon found himself staring at Cas. He had known since he was a teenager that he was bi, but he'd never told a soul. Not even Jess had known. He certainly hadn't told Dean. The rare male one-night-stands he'd had knew about it, of course – how could they not – but they were the only ones. Sam had been attracted to Cas since he'd first laid eyes on the guy, even though his personality at the time had been more than off-putting. Cas had changed a lot since then, though, so now Sam was afraid he was hopelessly in love with the angel for more than his amazingly good looks.

"Sam," he heard, causing his eyes to focus on the angel's eyes, which he had already been absentmindedly looking into.

"Yeah?" he asked.

"Is something wrong?" Cas questioned.

"Not at all," Sam said, feeling like maybe it wouldn't be so bad if Cas figured him out. Sam had always tried to keep his attraction towards the angel under the radar, but now he was wondering why.

"Is there a reason you're staring at me, then?" Cas asked. He didn't sound annoyed, just curious.

"Well, yeah, I guess there is," Sam answered. He had resolved himself to answering Cas's questions honestly, but not saying more than necessary. He realized he was drunk, and people do things they regret when they're drunk all the time, but if he didn't have to say more than Cas asked him to, there was nothing to regret, right? It wasn't like Cas would just ask him 'do you have a crush on me?' because Sam was pretty sure Cas didn't even know what a crush was. Which was funny, so Sam found himself laughing. Wow, he was inebriated. Inebriated sounded funny in his head, so Sam laughed some more.

"Sam, you are drunk," Cas observed.

"Well yeah. That's what happens in bars," Sam said. He didn't always get drunk, because Dean normally did, and they needed someone halfway sober for the way home, wherever home was at the time. Now they had Cas though, so Sam was pretty sure it was safe to get drunk.

"Sam, why were you staring at me?" Cas asked. He wasn't sure what was going on with Sam right now, but he wasn't sure what was going on with himself either. In all the thousands of years he had been in existence, he had never felt the way he was currently feeling toward any other human being, but something about Sam filled him with warmth. He also felt… nervous? It was almost as if he had insects squirming around in his vessel's innards. He'd thought about asking Dean what it was, because Dean would know. So would Sam, but he couldn't ask Sam because it was Sam who was making him feel this way.

"Because you're hot," Sam answered. It felt so good to get it off his chest that he didn't even care that Cas knew now.

Cas took a close look at Sam. He had been around humans long enough to know what that meant. And he had to admit he found Sam attractive as well. Of course, he knew objectively that Dean was an attractive person, but he didn't feel attracted to him the way he did Sam. Of course, according to society's standards, men weren't supposed to be attracted to other men. Although,, Cas wasn't technically a man… Deciding he needed to sake sure of exactly what Sam meant, he asked him, "Are you saying you are attracted to me?"

"Yeah, just a whole lot," Sam said.

Cas had to stop himself from asking if that meant they should start a relationship. Sam was drunk. It was not right to ask someone important questions like that when they were in the state Sam was in.

"I think I could use another drink," Sam suddenly said. He was thirsty.

"I think you've had enough," Cas said just as a waitress approached in response to Sam's hand signal.

"Can I get you anything?" she asked.

"No," Cas said before Sam could answer, "don't give him anything else." The waitress walked away without another word, and then Cas said to Sam, "Stay here, and don't order any more drinks. I'll be right back."

After searching the bar, Cas soon found Dean in the depths of a pool game, an attractive brunette nearly hanging off of him. As soon as Cas reached the table, Dean saw him and said, "What's up Cas?"

"Sam is very drunk," Cas said, telling himself that the conversation he had just had with the younger Winchester could wait for an explanation until after all parties concerned were sober.

"Well, I'm kind of in the middle of something here, so I can't really do anything right now," Dean said, making a suggestive look in the direction of the girl on his arm and the game in front of him. "Besides, Sam is old enough. He had a right to get drunk. You expect me to ground him or something?"

Cas wasn't completely sure what that meant, but he did note the sarcasm in the hunter's voice. "I don't expect you to do anything. I was planning on taking him to the motel room myself. I just thought you should know where we are going to be," Cas said.

"Alright. See you later," Dean said before turning his attention away from Cas.

After getting back to Sam, Cas grabbed his arm. "Come with me. I'm taking you home."

"Sounds great," Sam said, giggling.

As soon as they were out of the building and Cas knew no one would see them, he transported himself and Sam to the motel room. He immediately led Sam over to his bed and laid him down on it before taking off his boots and his jacket and pulling the covers over him. "Sleep Sam. We will talk in the morning."

"Yessir," Sam said with a goofy grin. He found himself falling asleep quickly despite not feeling tired moments ago.

Cas watched as Sam fell asleep. He decided to stay with him until Dean returned, just to make sure he was safe. Sam was, after all, in no position to defend himself if a monster came into the room, and that was not an unlikely prospect considering his profession. Deciding to do a very human thing as he waited for Dean to return, he turned on the television. He settled on watching the news.

* * *

Dean did not return that night. He arrived at the motel room about the time when Sam was making his way to the bathroom to empty the contents of his stomach. "Hey, Cas," Dean said. "Didn't think you'd still be here."

"I decided to wait until you got back to leave. I was concerned for Sam's safety. I did not think he should be left alone after getting so drunk. He didn't seem like he would have been capable of defending himself if something came into the room, so I decided I would defend him rather than let something happen to him. I have nothing better to do anyway."

"Alright, well thanks for looking out for us, but you don't always hang around at night."

"I never go far when I leave anyway. I normally take the time to observe human patterns and behaviors in order to improve my 'people skills'," Cas said, using air quotes which caused Dean to roll his eyes.

There was a groan from the bathroom at that time, giving Cas an idea. "Sam," he said, coming into the room, "if you would like I can calm all effects you feel from the alcohol you consumed last night."

"Please," Sam said. Cas promptly put two fingers to Sam's forehead and Sam immediately felt better once they were removed. "Thanks," he said.

"Anytime," Cas answered.

* * *

The rest of the day was spent doing nothing in particular. Cas was waiting until he got a chance to talk to Dean alone. It was time he got to the bottom of what he was feeling and the meaning behind what Sam had said at the bar. Sam, meanwhile, was trying to remember what had happened the night before. He was nervous about what he might have said. Dean, well, he was enjoying the downtime. It wouldn't be long before he was ready for another hunt, but he wasn't there just yet.

"I'm ready for lunch," Dean said at around one. "Who wants some?"

"I am indifferent," Cas said, as usual.

"I could go for some food," Sam said. Really, he should have known better.

"Alright. Why don't you go for some at that diner down the road. I want a hamburger, extra onion, and fries. And if they have pie, you know the drill."

"Why me?" Sam asked, even though he knew what he'd done.

"You said you could go for some food, so go," Dean said. Sam sighed, but got up and grabbed the keys before walking out the door. "Alright, lay it on me," Dean said to Cas as soon as the sounds of the Impala's engine faded into nothing.

"I'm sorry…?" Cas said, confused.

"You've obviously got something to say to me. You may not realize it, but you aren't exactly subtle," Dean said.

"Right," Cas said, not realizing he'd been so obvious. "I… last night, Sam said some things, when he was drunk, and I'm not sure how I feel about it. I mean, I know how I feel, but I don't know what the feelings I'm feeling are called or what they mean and I thought I should ask you because I'm sure you would know, and of course Sam would know as well, but I didn't feel comfortable asking him about this—"

"Hold on a second," Dean said. This couldn't be going where he thought it was. "What exactly did Sam say to you?"

"Well, it started with him staring at me, and when I asked him why, his exact words were, 'because you're hot.' I proceeded to ask him if he was indicating whether he found me attractive. I guess I just wanted to make sure he meant what I thought he meant. His next words were, 'yeah, just a whole lot.'"

Dean took a moment to try to absorb this. Apparently, Sam wasn't as straight as he'd thought. Which was ok, it just surprised him. He kind of wished Sam would have told him, but considering the world they lived in he couldn't blame him, really. "Ok, so Sam likes you," Dean said, more to himself than to Cas.

"Well of course he likes me," Cas said. "We are friends after all."

"No, not like that. I mean, he _likes_ you. It's like… the same thing as him thinking you're hot," Dean tried to explain.

"I see," Cas said, though he wasn't sure he did.

"So, the feelings you have about this…" Dean prompted.

"Right," Cas said. "Well, I enjoy being around Sam. I enjoy being with you as well, of course, but it's different with Sam. I also feel warm when I'm with him, but it's as if I have insects inside of me, like there is a burning within me."

"Holy crap," Dean said. "You like Sam."

"You mean, I'm attracted to him?"

"Yes, Cas, that's what I meant," Dean said. "Wow, this is weird. Ok, so you're attracted to Sam. What do you want to do about it?" Dean asked.

"I'm not sure what you mean," Cas said. It almost sounded like Dean was asking how he wanted to make himself stop being attracted to Sam, but he wasn't sure he wanted that.

"I mean, do you want to talk to him about all this, or do you want to just ignore it, or what?"

"I suppose talking to him would be good. Should I tell him what was said last night?"

"That's completely up to you. I just don't want to be in the room when you talk to him," Dean said.

"Ok," Cas said. "The next time we are alone I will talk to him."

"Alright. Tell you what. I'll go grab dinner and let the two of you have some time. How's that sound?"

"Good," Cas said, just as Sam walked in the door.

"Tell me how it goes," Dean said. Sam gave them both a strange look, but didn't ask.

* * *

That night around 7:30, true to his word, Dean announced he was leaving to find some food. Once he was sure Dean was gone, Cas said, "Sam, we need to talk about something."

"Ok," Sam said. "This doesn't sound too good."

"Last night, when you were drunk, you said some things, and I believe they should be discussed."

Sam cringed. This definitely wasn't good. He had to keep cool though. Maybe nothing had really happened. "What did I say, exactly?"

"Well, you told me that I was… hot, and that you were… attracted to me," Cas mumbled, but Sam heard him loud and clear.

Sam felt like he might panic. This was awful. Nobody even knew he liked guys, and now he had just confessed to Cas that he was in love with him. There was no way he could play this off as nothing. What must Cas think of him? He already considered him an abomination.

"I feel you should know," Cas started, making Sam feel worse, "that I feel the same way towards you."

With those last words, Sam's world came to a stop. He had never expected anything to come of his feelings for Cas. He certainly hadn't expected his feelings to be reciprocated. Hearing this was the best thing he could have hoped for. He just wasn't sure how he should feel about it. Happy seemed to be the obvious answer, but that was too easy. This was more complicated than that. What would Dean think? As much as he would like to say it didn't matter what his brother thought, this was his life, he should be able to make decisions based on what he wanted – well, Dean mattered too much for him to think that way and he didn't want to hurt his brother. _That's stupid_ , Sam thought. _Dean's not the one who's in danger of being hurt here. He might not be happy with this, but there's not much room for him to be hurt. I'm just afraid of being hurt because I love him so much._

"Sam?" Cas asked. "Is this ok with you?"

Realizing he'd been silent for too long, Sam said, "Yeah, this is great, actually. I never would have imagined something as amazing as this. I mean, I was never planning to tell you I thought I was in love with you, and I certainly never imagined you would feel the same way. I'm just a little shocked. I don't really know what to expect, or what to do next."

"It is my understanding that when two humans feel this way about one another, they enter into a relationship in which they go out on dates, meaning they see movies and eat meals together, and sometimes have sex afterwards. Is this correct?"

Sam smiled at Cas's wording. "Yeah, pretty much, but if it's all the same to you, let's wait a while for the sex. A kiss doesn't sound awful though."

No sooner had the words left Sam's mouth than Cas's lips were pressed to his in a kiss. It wasn't the most chaste kiss Sam had ever shared with someone, but it wasn't too deep either. It was sheer perfection. For some reason, Sam hadn't expected an Angel of the Lord to be a great kisser, but he'd been wrong. "So, you wish to start a relationship?" Cas questioned once their lips parted.

"Yeah," Sam said, nearly out of breath from the greatness of what had just happened. "So, what are we calling this? Like, are we going to be boyfriends?"

"That is what it is called is it not?" Cas asked.

"Yeah, pretty much," Sam agreed. "God, what is Dean going to think about all of this?"

"Well, he already knows, in a way," Cas said. "After what happened last night, I wasn't sure exactly what to do, or even what I was feeling, so I went to your brother. He explained that you 'like' me, and that I 'like' you and said that we should talk. That is why he left to get dinner – so we could talk in private."

"Great," Sam said. "So what did he seem to think about the fact that I like a guy?"

"He didn't say. He didn't seem to have an issue with it, though."

"That's good. I wasn't sure what he would think about me not being straight. I hope he isn't mad I didn't come clean to him."

"If he is, I don't believe he will stay angry for very long," Cas assured Sam.

"Yeah, I guess you're right," Sam agreed, hoping it was true.

When Dean came in the door, Sam and Cas weren't saying anything, so he was a little worried. "Everything ok?" he asked them.

"It's great, actually," Sam said. "Cas told me about what the two of you apparently already discussed. We decided to be boyfriends. Is this all good with you?" Sam asked. There had been plenty of times he'd knowingly done stuff against his brother's wishes, but the fact was he still really wanted his brother's approval when it came to the important things.

"Yeah, I'm fine with it. You could have told me you liked guys though," Dean said.

"I know that now, but I was afraid."

"I can understand that, and I don't hold it against you," Dean said, because he'd had time to think this through and he already knew what he was going to say. "In the future, though, remember you can always tell me anything, alright?"

"Yeah," Sam said with a smile.

The next time Dean had a moment alone with Cas, he made sure to tell him what would happen to him, in great detail, if he screwed with his little brother's heart.

* * *

 _ **AN: That's all until the epilogue. I've already written it, so it should be up soon. I don't know when the rest of the story will be posted, but since this didn't really end with a cliffhanger I will probably take my time with it. It may come really fast though. We'll just have to see, won't we?**_


	2. Epilogue

_**AN: Here's the epilogue! I thought this just kind of seemed like it should happen. This is basically Sam and Cas talking about life.**_

 _ **Disclaimer: I don't own it.**_

It was three days after his and Cas's declarations of love towards one another that it hit Sam what had happened. He had just told an angel that they could be boyfriends, and they had left it at that. There had been no further discussion of what that meant. Cas had mentioned dinner and movies and sex, which all sounded good, although Sam did like to wait for a little while to have sex when it came to serious relationships. Things tended to turn out better that way. That's how he'd done it with Jess, and not how he'd done it with Ruby, so he figured it was a pretty safe bet to wait a while… Really, though, they needed to talk about what all of this meant to them. So he kicked Dean out of the motel room.

"What do you mean?" Dean asked when Sam told him to find something to do away from the motel for the next few hours.

"I mean, Cas and I have some stuff we need to talk about, and we don't need you around for it, so go to a bar—"

"It's three in the afternoon!" Dean interrupted.

"Or go to a coffee shop and check out the coeds—"

"I'm not a perv!" came the second interruption.

"Or go eat some food—"

"I'm not hungry!"

"Or just do something to give us time to talk. I'll call when we're done and you can come back," Sam said, shoving his brother out the door after pushing his car keys into his hand. He leaned against the door until the sounds of the Impala faded out completely. "Finally," he breathed.

Cas looked at him from where he'd been sitting on one of the beds, watching the exchange. "What is it we need to discuss?" he asked.

"Just about everything," Sam said. "Look, we haven't really established what it is we have between us. I mean, I know we say we're boyfriends, but we haven't really been over what that means to us, so we need to go over it," Sam said.

"Ok," Cas said.

"Well, here's what I'm thinking. We need to establish that we aren't going to see anyone else. We only kiss each other, only look at each other in any type of romantic sort of way, no flirting with other people… you get the idea?"

"Yes, I understand," Cas said.

"Good. Alright, next thing is sex. I see this as a somewhat serious relationship," Sam said, feeling a little awkward talking about sex with the angel. Yeah, he'd had some fantasies involving the guy, but he wasn't the type he'd ever expected himself to talk about sex with, even if he wasn't talking in great detail about the act itself. "Because I see this like that, I think it would be wise to wait at least a few weeks before we sleep together," Sam said.

"I agree," Cas said. "There is something you should know, though."

"Ok," Sam said.

"First, I have to ask you a question, and it will sound strange, but the answer is pertinent to this conversation. I believe the correct wording is, do you prefer to bottom or to top? I have no preference myself."

Sam nearly choked, but recovered himself quickly enough. "I've only topped with women. If I'm with a man, I prefer to bottom."

"Well, in that case, you should know that if we have sex, and you bottom, you are at a high risk of becoming pregnant." When Sam only stared at him, Cas elaborated. "Any living being who sleeps with an angel and takes in semen from that angel, whether the being is male or female, can become pregnant, the same as any male and female human having intercourse. There is a certain amount of grace that is in an angel's semen, a certain type that is made just for this and has no effect on the angel himself, that would change your body to allow it to carry a child. You would carry the child for the usual nine months, and deliver it through a birth canal that would form. Over the next year, the birth canal would gradually shrink until it disappeared, unless you became pregnant again in that year. Of course, if you do not wish to have children, we can use a condom each time."

"Well that's a lot to take in," Sam said. "I guess I'm gonna have to say no on the kids for now. There's another thing I just thought of. Jimmy Novak, the human who lived in your vessel, is he still around?"

"No, he has gone to heaven. I am the only one inside here now," Cas said.

"That's good, because I wouldn't want to have sex with his body if he was still inside it."

"You are a good man, Sam Winchester," Cas said.

Sam looked down almost shyly at the compliment, but Cas let him. "Another thing we should talk about," Sam said after enough time had passed. "I don't think we should keep any secrets. I want both of us to be completely honest with each other."

"That sounds like a fair agreement," Cas said. "Speaking of which, would it bother you if I were to ever read your mind? As I'm sure you know, I have the ability, but I can refrain from doing it if you wish."

"I'd rather you didn't read my mind. Not unless I tell you that you can," Sam said. He was more than willing to be honest with Cas, but something about having his mind read just didn't completely sit right with him.

"Very well," Cas said. "There is something else I think you should know while we are discussing these things. I am trying to adjust to human concepts of relationships, so I feel this is reasonable of me to suggest. When angels are in serious relationships, they become mates. This is done through a ritual. We would not have to do it by any means, but if you are willing, I would like to do it. It would essentially create a bond between us. This bond would allow us to communicate telepathically, without the use of mind-reading. It would also allow you to see my wings at all times. And we would be able to… feel one another. In other words, I would be able to sense your emotional state if the two of us were within a 10 mile radius of one another, and you would be able to do the same. Again, this is not like mind-reading. We would just know if the other of us were stressed, happy, frightened, excited, and so forth."

"You say angels do this when they are in a serious relationship. How serious would this have to be? I mean, I hate to be pessimistic, but what if something happens and this thing doesn't work out? What if we changed our minds about what we wanted?"

"My apologies," Cas said. "I didn't explain that very well. Mating for angels is a bit like marriage to humans. After a serious relationship has lasted for a certain amount of time – this amount of time would be decided by the two involved in the relationship – the two would perform the ritual, greatly strengthening and increasing the small bond that would already exist. So this would be something we would do in time. I just thought it would be fair to suggest it now so that you would have ample time to consider it."

"Oh, ok. That makes me think of something else. What do you think about marriage? Like you said with the whole mating thing, this would be a ways down the road."

"I would like to marry you one day, Sam," Cas said.

"I feel the same," Sam said, surprising himself. It was the truth, though. When neither of them had anything else to say over the next few minutes, Sam finally said, "Well, I guess we've settled all this now. I'll call Dean and tell him he can come back."

The End  
(For now)

* * *

 ** _AN: If you think something else should have been discussed, or if you have any other feedback, let me know! I'm about 1/3 of the way through the story now, but with school starting I would say you can expect it to start coming up in the next couple months...?_**


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